JP2014134448A - Magnetic property measuring device, magnetic property measuring probe, and magnetic property measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic property measuring device which easily measures a magnetic property of a high-permeability magnetic material before, after, and during heat treatment in a nondestructive manner.SOLUTION: A magnetic property measuring device 10 includes: a magnetic property measuring probe 1 including a magnetic core 2 formed by laminating ribbon-shaped amorphous magnetic bodies, an exciting coil 4 exciting the magnetic core 2, and a detecting coil 5 detecting an induced voltage waveform due to an excitation magnetic flux; and a harmonic measuring circuit 12 which fetches and processes the induced voltage waveform detected by the magnetic property measuring probe 1 so as to measure a harmonic of the induced voltage waveform.

Description

  The present invention relates to a magnetic property measuring apparatus, a magnetic property measuring probe, and a magnetic property measuring method for measuring magnetic properties of a high permeability magnetic material.

  Permalloy, Fe-Si-Al alloy, silicon steel, 6.5% silicon steel, electromagnetic soft iron, magnetic stainless alloy, Fe-based amorphous alloy, Co-based amorphous alloy, nanocrystalline soft magnetic material, etc. are called high permeability magnetic materials . These high-permeability magnetic materials are generally heat-treated to increase the magnetic permeability and reduce the coercive force, whereby higher performance magnetic materials can be obtained. Further, by appropriately controlling the heat treatment conditions, desired magnetic characteristics including an intermediate processing state can be realized and used for various applications.

  There are various methods for measuring magnetic properties. (1) A method of obtaining BH magnetization characteristics by a BH analyzer and reading coercive force and permeability, and (2) Magnetization characteristics (magnetic field H dependence of magnetization M) by a vibrating sample magnetometer (VSM). (3) A method of measuring the coercive force with a desktop coercometer simplified only to measure the coercive force at room temperature with a vibrating sample magnetometer, 4) A method for obtaining magnetic permeability from self-inductance by an impedance analyzer.

  In order to measure magnetic properties by these methods, the following measurement samples are required. In the case of using the BH analyzer of (1), a sample to be measured is formed by cutting out a ring-shaped test piece from a target magnetic material and winding an excitation coil and a detection coil on this with an insulation-coated copper wire. Need to create. In the case of using the vibrating sample magnetometer of (2) and (3), it is necessary to cut out a small piece of several mm to several tens of mm, and in order to maintain measurement reproducibility, for example, 10 mm diameter × 50 mm length or 20 mm diameter It must be processed into a certain shape, such as x30 mm length. In the case of using the impedance analyzer of (4), it is necessary to cut out a test piece into a ring shape and wind an insulation-coated copper wire around this to make a coil, as in (1).

  Also, (1) and (2) are large and expensive as a measuring device. (3) and (4) are smaller and less expensive than these, but the characteristics that can be measured are limited.

  Here, for example, in the manufacturing process, it may be necessary to measure and determine whether or not the magnetic properties of such a high permeability magnetic material are desired. However, using any of these measuring instruments and measuring systems, the sample to be measured must be cut out from the high permeability magnetic material to be measured. In the manufacturing process, predetermined magnetic properties are obtained before and after heat treatment. It is very difficult to measure for each product. Further, since the high magnetic permeability material has a large degree of deterioration in magnetic characteristics due to processing strain, when the test piece is cut out, there is a high possibility that the test piece does not represent the target high magnetic permeability magnetic material. Moreover, if the magnetic properties of a high permeability magnetic material can be easily and non-destructively known, it is very convenient in the field of research and technical development. And if it is possible to determine whether the high-permeability magnetic material is heat-treated or in an intermediate processing state without accurately measuring magnetic properties such as magnetic permeability, the determination during the manufacturing process It is easy to work and is also useful as a material evaluation means.

  Patent Documents 1 and 2 disclose methods for measuring magnetic properties without cutting out a sample to be measured.

JP-A-6-331718 JP 2011-123081 A

  In Patent Document 1, a probe for measuring an inductance value by bringing two yokes each provided with an excitation coil and a detection coil into contact with or close to the surface of a high permeability material to be measured is used. A method for measuring the magnetic permeability of a magnetically permeable material is described. According to the magnetic characteristic measurement method described in Patent Document 1, the yoke and the high permeability material to be measured are configured by bringing two yokes into contact with or close to the surface of the high permeability material to be measured. Since the magnetic permeability of the high magnetic permeability material to be measured is measured by the magnetic circuit to be measured, the magnetic permeability can be measured nondestructively. Therefore, if the magnetic permeability before and after the heat treatment or in the intermediate state is known in advance, it is possible to know what state the high permeability material to be measured is in.

  However, in the measuring method described in Patent Document 1, the magnetic permeability is measured by measuring the inductance of the magnetic circuit under two types of magnetic circuit conditions and solving the simultaneous equations. For this reason, two yokes are essential, the measurement system becomes complicated, and the procedure is complicated. On the other hand, the permeability changes depending on the physical dimensions of the high permeability material to be measured, so measure several types of physical dimensions and permeability in advance and check whether these values match or approximate. There is a problem that it is necessary to make a judgment one by one and the work is complicated. In addition, in order to accurately measure the magnetic permeability, it is necessary to apply a somewhat large magnetic field to the sample, and there is a problem that the scale of the measurement system, for example, the power supply capacity for excitation, must be increased.

  In Patent Document 2, an excitation coil and a detection coil are wound around a U-shaped magnetic core, and the end of the magnetic core is placed close to and opposed to the magnetic body to be measured. A method for measuring magnetic susceptibility is described.

  However, in the magnetic characteristic measurement method disclosed in Patent Document 2, in order to measure the complex permeability as the magnetic characteristic, the measurement system requires a phase detection function, and the configuration of the measurement apparatus is complicated. is there.

  Therefore, the present invention provides a magnetic property measuring apparatus that simply measures the magnetic properties of a high permeability magnetic material in the intermediate state before and after heat treatment, and easily determines the degree and presence of heat treatment. With the goal.

  A magnetic characteristic measuring apparatus according to an embodiment of the present invention includes a magnetic body having both ends, a first coil magnetically coupled to the magnetic body, and a magnetic body magnetically coupled to the magnetic body at a position different from the first coil. A magnetic characteristic measuring probe having a second coil, a power source for exciting a magnetic material by supplying a sinusoidal excitation current to the first coil, and an induced voltage waveform generated in the second coil by the excitation current And a harmonic measurement circuit that measures harmonics from the induced voltage waveform. Then, both ends of the magnetic material are brought into contact with the magnetic material to be measured, a closed magnetic circuit is formed with the magnetic material, and the harmonics of the induced voltage waveform are measured, thereby measuring the magnetic characteristics of the magnetic material to be measured.

  A magnetic characteristic measuring probe according to an embodiment of the present invention includes a magnetic body having both ends, a first coil magnetically coupled to the magnetic body, and a magnetic body magnetically coupled to the magnetic body at a position different from the first coil. And a second coil. The first coil is driven by a power source that generates a sine wave current, and the second coil outputs an induced voltage generated via the magnetic material excited by the first coil, Both ends are brought into contact with the magnetic substance to be measured to form a closed magnetic circuit with the magnetic substance, and the harmonics of the induced voltage are measured to measure the magnetic characteristics of the magnetic substance to be measured.

  According to one embodiment of the present invention, there is provided a magnetic property method comprising: a magnetic body having both ends; a first coil magnetically coupled to the magnetic body; and a magnetic body magnetically coupled to the magnetic body at a position different from the first coil. Both ends of the magnetic body of the magnetic characteristic measuring probe having the second coil are brought into contact with the magnetic body to be measured so as to form a closed magnetic circuit with the magnetic body, and a sine wave current is supplied to the first coil by the power source. Then, the magnetic material is excited, the induced voltage generated in the second coil by the excited magnetic material is acquired by the harmonic measuring circuit, and the harmonic is measured from the induced voltage.

  Since both ends of the magnetic material are in contact with the surface of the magnetic material to be measured, a closed magnetic circuit is formed and the harmonics of the induced voltage waveform are measured, so the high permeability magnetic material in the intermediate state is not destructed before or after heat treatment. The magnetic properties can be measured easily.

It is a block diagram which shows the structural example of the magnetic characteristic measuring apparatus of one Embodiment which concerns on this invention. It is the front view ((A) figure) and side view ((B) figure) which show the structural example of the magnetic characteristic measuring probe of one Embodiment which concerns on this invention. It is a conceptual diagram for demonstrating the measurement principle of the magnetic characteristic measuring apparatus with which this invention was applied. It is a graph of the magnetization characteristic of PC permalloy before and after heat treatment. (A) shows the magnetic properties of the heat-treated material, and (B) shows the non-heat-treated magnetic properties. It is the graph which measured the magnetic permeability with respect to the intensity | strength of the magnetic field of PC permalloy before and behind heat processing. (A) shows the heat-treated, and (B) shows the non-heat-treated. An excitation current waveform ((A) diagram) and an induced voltage waveform ((B) diagram) when a PC permalloy sample after heat treatment is measured using the magnetic property measuring apparatus according to one embodiment of the present invention. ). An excitation current waveform ((A) diagram) and an induced voltage waveform ((B) diagram) when a non-heat-treated PC permalloy sample is measured using the magnetic property measuring apparatus according to one embodiment of the present invention. ). 500 Hz excitation current waveform ((A) diagram) and induced voltage waveform ((B) diagram) when a PC permalloy sample after heat treatment is measured using the magnetic property measuring apparatus according to one embodiment of the present invention. ). 500 Hz excitation current waveform ((A) diagram) and induced voltage waveform ((B) diagram) when a non-heat-treated PC permalloy sample is measured using the magnetic property measuring apparatus according to one embodiment of the present invention. ). 2 kHz excitation current waveform ((A) diagram) and induced voltage waveform ((B) diagram) when a PC permalloy sample after heat treatment is measured using the magnetic property measuring apparatus according to one embodiment of the present invention. ). 2 kHz excitation current waveform ((A) diagram) and induced voltage waveform ((B) diagram) when a non-heat-treated PC permalloy sample is measured using the magnetic property measuring apparatus according to one embodiment of the present invention. ). It is a graph which shows the frequency characteristic at the time of exciting at 500 Hz when measuring the sample of PC permalloy before and behind heat processing using the magnetic characteristic measuring apparatus of one embodiment concerning the present invention. (A) The figure is the graph which plotted the thing of non-heat processing after (B) figure after heat processing. Using the magnetic property measuring apparatus according to one embodiment of the present invention, harmonics are measured, and the ratio of the third harmonic / fundamental wave before and after heat treatment when the excitation frequency is 500 Hz and 2 kHz. FIG. It is a block diagram which shows the structural example of the magnetic characteristic measuring apparatus of 2nd Embodiment which concerns on this invention.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited only to the following embodiment, Of course, a various change is possible in the range which does not deviate from the summary of this invention.

[Configuration of magnetic characteristic measuring apparatus and probe]
As shown in FIG. 1, a magnetic property measuring apparatus 10 according to a first embodiment to which the present invention is applied includes a magnetic core 2 in which thin ribbon-like amorphous magnetic bodies having a certain width are stacked, and a magnetic core 2. A single magnetic characteristic measurement probe 1 having an exciting coil 4 for exciting and a detecting coil 5 for detecting an induced voltage waveform caused by exciting magnetic flux is provided. The magnetic characteristic measurement apparatus 10 includes a harmonic measurement circuit 12 that takes in the induced voltage waveform detected by the magnetic characteristic measurement probe 1, processes the waveform, and measures harmonics of the induced voltage waveform.

  As shown in FIGS. 2 (A) and 2 (B), the magnetic core 2 of the magnetic property measurement probe 1 forms a closed magnetic circuit so as to be in contact with any two points on the surface of the magnetic substance 9 to be measured. Configure the magnetic circuit. For this reason, the magnetic property measuring probe 1 is formed in a “U” shape or a “U” shape along the longitudinal direction of the magnetic core 2 so as to contact any two points on the surface of the magnetic body 9 to be measured. It is preferable to bend and mold. Further, the tips 3 and 3 of the magnetic core 2 are preferably bent into a J shape. By forming the tips 3 and 3 into a J shape, the elasticity of the magnetic core 2 itself and the tips 3 and 3 are obtained. Due to the elasticity of the J-shaped part, it is possible to make the magnetic body 9 to be measured adhere to. In the present specification, the U-shape is included in the U-shape.

  The magnetic core 2 is preferably formed of a high magnetic permeability soft magnetic material, and more preferably a Co-based amorphous magnetic material so that it can be excited with a lower excitation current. The Co-based amorphous magnetic material is generally provided as a thin strip having a thickness of 0.015 to 0.025 mm, and the number of stacked layers can be increased or decreased by stacking the thin strip-shaped magnetic materials. The core cross-sectional area of the magnetic core 2 can be set by adjusting the number of layers of the Co-based amorphous magnetic material. In a Co-based amorphous magnetic material, higher magnetic properties can be realized by performing heat treatment at a temperature that is higher than the Curie temperature and lower than the crystallization temperature and that is as high as possible in a temperature range that does not crystallize and is as far as possible from the Curie temperature. However, when heat treatment is performed at a high temperature, it becomes brittle even if it becomes brittle, so that it becomes difficult to process. Therefore, in the Co-based amorphous magnetic material, high magnetic properties and workability can be achieved by performing heat treatment at a relatively low temperature that does not greatly exceed the Curie temperature. Specifically, for example, in ACO-5 (manufactured by Hitachi Metals), by performing heat treatment at 210 ° C. (Curie temperature 210 ° C.) for 1 hour, the relative permeability at a frequency of 1 kHz and an applied magnetic field of 0.4 A / m is obtained. It can be increased to about 15000 to 20000 with respect to about 10,000 in the absence of heat treatment. In addition, it cannot be overemphasized that other high permeability magnetic materials can be used for the magnetic core 2 besides Co-based amorphous magnetic material.

  The above is an example, and the required workability differs depending on the shape of the magnetic core, and there are various types of amorphous magnetic materials, and the Curie temperature and crystallization temperature may be different. And the balance of workability must be adjusted. However, in order to maintain the workability for the purpose of the present invention and improve the characteristics without heat treatment by 50 to 100%, heat treatment at a Curie temperature of 50 ° C. or higher and at most, a Curie temperature of 100 ° C. or higher is possible. desirable.

  The excitation coil 4 and the detection coil 5 are arranged at any position of the magnetic core 2 so as to be linked to the magnetic path of the magnetic core 2. In order to prevent each coil from magnetically coupling to the other due to the leakage magnetic flux of the excitation coil 4 and the detection coil 5, a physical distance between the excitation coil 4 and the detection coil 5 is increased. It is preferable to arrange. For example, as shown in FIG. 1, when the magnetic core 2 is formed in a U shape, it is preferable that the magnetic core 2 be disposed near the ends 3 and 3 of the magnetic core 2. It is also possible to take a physical distance between the exciting coil 4 and the detecting coil 5 by molding the magnetic core 2 into an “Ω” shape.

  A wiring 7 for electrical connection of the excitation coil 4 and a wiring 8 for electrical connection of the detection coil 5 are drawn out and connected to a power source 11 and a harmonic measurement circuit 12, respectively.

  In order to protect the magnetic core 2 and the wirings 7 and 8 from the external environment while safely holding the magnetic core 2 formed of the ribbon-shaped Co-based amorphous magnetic material, the magnetic core 2, the exciting coil 4, The detection coil 5 and the wires 7 and 8 are preferably housed in the probe case 6. The probe case 6 needs to be formed of a non-magnetic and electrically insulating material. The probe case 6 is formed by injection molding using a molding die using any synthetic resin such as ABS resin or PVC resin. The probe case 6 is formed so that the magnetic core 2 is housed together with the excitation coil 4 and the detection coil 5 and only the tips 3 and 3 are exposed. One end of the wires 7 and 8 is pulled out from the probe case 6 for external connection. Needless to say, the probe case 6 can be formed of any other material and shape for the above-described purpose.

  The harmonic measurement circuit 12 is used to analyze the induced voltage waveform detected by the detection coil 5 of the magnetic characteristic measurement probe 1 through the wiring 8 and the acquired waveform data in the frequency domain. And an FFT unit 14 for performing Fourier transform. The harmonic measurement circuit 12 performs signal processing on the induced voltage waveform data Fourier-transformed by the FFT unit 14 to calculate a harmonic component, and the data analyzed by the waveform analysis unit 15. And a result output unit 16 that outputs the next harmonic component value. The waveform capturing unit 13 includes an A / D converter that receives an induced voltage waveform that is an analog signal output from the detection coil 5 via the wiring 8 and converts the waveform into a digital signal for subsequent signal processing. . The FFT unit 14 converts the time domain data of the induced voltage waveform converted into a digital signal into frequency domain data. The waveform analyzer 15 measures the voltage level of the fundamental wave component of the acquired induced voltage waveform and the frequency component corresponding to the harmonic order. The result output unit 16 reconstructs the voltage level data with respect to the frequency thus obtained and calculated, and displays the text as frequency analysis data, for example, on a display screen or as graphic data as plot data.

[Measurement Principle and Operation of Magnetic Characteristic Measuring Device]
As shown in FIG. 3, the tips 3 and 3 of the magnetic core 2 are arranged so as to contact any two points of the magnetic body 9 to be measured. By bringing the magnetic core 2 and the magnetic substance 9 to be measured into contact with each other, a closed magnetic circuit is formed as shown by the one-dot chain line and the broken line in FIG. A power supply 11 is connected to the excitation coil 4 via a wiring 7, the power supply 11 outputs a sine wave current like a waveform 11 a, and the excitation coil 4 is driven by a sine wave. The magnetic core 2 is excited by the magnetic flux interlinking with the exciting coil 4, and the induced voltage waveform 12 a similar to the waveform of the magnetic flux flowing in the closed magnetic circuit is connected to the wiring 8 by the detection coil 5 magnetically coupled to the magnetic core 2. Is output via.

  Here, the difference in magnetization characteristics between the high permeability magnetic material subjected to heat treatment and the high permeability magnetic material not subjected to heat treatment will be described.

  FIG. 4 shows the result of measuring the BH magnetization characteristics of a PC permalloy measurement sample formed in a ring shape in advance for measuring magnetic characteristics. The magnetization curve in FIG. 4A is that of a ring-shaped measurement sample after heat treatment, and FIG. 4B is the magnetization curve of the ring-shaped measurement sample before heat treatment. In these cases, the profiles of the magnetization curves are greatly different. As can be seen from these figures, the sample after the heat treatment has a smaller coercive force and a higher residual magnetic flux density than those before the heat treatment. In addition, the sample after the heat treatment is magnetically saturated at a lower magnetic field, whereas the non-heat treated sample tends to hardly reach the magnetic saturation. That is, it can be seen that the sample subjected to the heat treatment is more easily magnetized and has a smaller pinning with respect to the domain wall in a low magnetic field.

  Further, FIG. 5 is obtained by converting the BH magnetization characteristics (magnetic field-magnetic flux density) of FIG. 4 into μ-H characteristics (relationship between magnetic field and magnetic permeability). It can be seen that the magnitude of the magnetic permeability with respect to the strength of the magnetic field also varies depending on the presence or absence of heat treatment. FIG. 5A shows the measurement result of the same PC permalloy measurement sample as described above after the heat treatment, and FIG. 5B shows the measurement result of the sample having the same shape before the heat treatment. Before and after the heat treatment, the change in permeability with respect to the strength of the magnetic field is in the opposite direction. That is, in the heat-treated product, the magnetic permeability decreases as the magnetic field increases, and in the pre-heat-treated product, the magnetic permeability increases as the magnetic field increases. This is because, in the BH magnetization characteristics of FIG. 4, the heat-treated product has a steep rise in magnetization in a small magnetic field region and magnetically saturates quickly, whereas the non-heat-treated product has a slow rise in magnetization and slow magnetic saturation. Is reflected. Therefore, by measuring the magnetization characteristics in a relatively weak magnetic field, the difference in magnetic permeability depending on the presence or absence of heat treatment or the degree of heat treatment can be made obvious. Here, when directly measuring the magnetization characteristics, a precise and high-power measurement system as disclosed in Patent Document 1 is required. However, the difference in magnetic characteristics before and after the heat treatment is small magnetic field, that is, low power. Since it is remarkable and the difference in the degree of change in magnetic permeability is remarkable, a small-scale and low-power measurement system can be constructed.

  Specifically, as shown in the induced voltage waveform 12a in FIG. 3, the induced voltage waveform detected by the detection coil 5 is a waveform distorted due to nonlinearity of the magnetization characteristics with respect to the input sine wave. . In the high magnetic permeability magnetic material subjected to the heat treatment, the change in the magnetic permeability of the low magnetic field is particularly large and the degree of nonlinearity is large. Therefore, the difference in magnetization characteristics can be measured by harmonic analysis of the degree of distortion of the induced voltage waveform detected from the detection coil 5, and the presence or absence of heat treatment and the degree of heat treatment can be determined.

[Measurement result]
6 to 11 show graphs (each diagram (B)) obtained by measuring the induced voltage waveform 12a detected from the detection coil 5 in the high permeability magnetic material with and without heat treatment, and excitation current waveforms (each diagram ( A)) is shown in contrast.

  In the following measurement, the magnetic property measurement probe 1 is laminated with 20 ribbons of a Co-based amorphous magnetic material having a width of 3 mm × about 60 mm, bent in a U shape along the longitudinal direction, and the tip is J-shaped. A magnetic core 2 bent in a shape is used. The excitation coil 4 and the detection coil 5 are made by winding 100 turns of urethane-coated Cu wire with a diameter of 100 μm for 100 turns.

  The measured magnetic body 9 is a 1 mm thick, 100 mm square plate of the PC permalloy used above. The heat treatment applied to the sample below is 1100 ° C. for 4 hours.

  FIG. 6 is a graph obtained by measuring the induced voltage waveform of the heat-treated product when the excitation current frequency is 50 Hz.

  FIG. 7 is a graph obtained by measuring the induced voltage waveform of the non-heat treated product under the same conditions as in FIG.

  Comparing FIG. 6 and FIG. 7, it can be seen that the distortion of the induced voltage waveform is larger in the case of FIG. 6 where the heat-treated product is measured. The harmonic component of the induced voltage waveform is also expected to be larger in the case of FIG.

  FIG. 8 is a graph obtained by measuring the induced voltage waveform of the heat-treated product when the excitation current frequency is 500 Hz.

  FIG. 9 is a graph obtained by measuring the induced voltage waveform of the non-heat treated product under the same conditions as in FIG.

  Comparing FIG. 8 and FIG. 9, it can be seen that the distortion of the induced voltage waveform and the harmonic component are larger in the case of FIG.

  FIG. 10 is a graph obtained by measuring the induced voltage waveform of the heat-treated product when the excitation current frequency is 2 kHz.

  FIG. 11 is a graph obtained by measuring the induced voltage waveform of the non-heat treated product under the same conditions as in FIG.

  When FIG. 10 is compared with FIG. 11, it can be seen that the distortion of the induced voltage waveform is larger and the harmonic component is larger in the case of FIG.

  FIG. 12 shows the high permeability magnetic material before and after the heat treatment under the conditions shown in FIGS. 8 and 9, that is, the induced voltage waveform obtained when the excitation current frequency is 500 Hz, and quantitatively shows the harmonic content. It is a graph which shows the result converted into the voltage level of a frequency using a spectrum analyzer. FIG. 12A shows the result of measuring the heat-treated product, and FIG. 12B shows the result of measuring the non-heat-treated product. It can be seen that the heat-treated product shown in FIG. 12A has higher odd-order harmonics such as the third harmonic and the fifth harmonic than the non-heat treated product shown in FIG.

  From the above, by measuring the harmonic component of the induced voltage detected by the single magnetic property measuring probe 1, it is possible to determine whether the sample is heat-treated or in an intermediate state. It is. The change in the magnetization curve of PC permalloy before and after the heat treatment and the change in permeability with respect to the magnetic field are as shown in FIGS. 4 and 5, respectively. It is considered that the difference in magnetic field dependence of magnetic susceptibility appears as a difference in distortion of the detected harmonic waveform. It can be seen that the heat-treated sample is more easily magnetized and has less pinning with respect to the domain wall in a low magnetic field.

  As shown in FIG. 13, since the third harmonic / fundamental wave has a difference of about 2: 1 between the heat treated PC permalloy and the non-heat treated product, the third harmonic / fundamental wave is measured. By setting the threshold value as a variable, for example, 0.15 or more (f = 500 Hz) or 0.12 or more (f = 2 kHz), it is possible to make a simple determination as to the presence or absence of heat treatment.

  It should be noted that the threshold for performing the simple determination as described above is measured for each magnetic material and is determined for each magnetic material. Needless to say, it is necessary to measure and set an appropriate threshold value in advance using a sample whose heat treatment conditions are known.

[Configuration Example of Second Embodiment]
As described above, in the embodiment according to the present invention, when a magnetic property difference before and after heat treatment is measured using a magnetic property measurement probe, it is realized by using a simpler harmonic measurement circuit. Can do.

  As shown in FIG. 14, the magnetic characteristic measuring apparatus according to the second embodiment to which the present invention is applied includes a magnetic core 2 in which a thin ribbon-like amorphous magnetic material is laminated, and magnetic cores near both ends of the magnetic core 2. 2, a magnetic characteristic measurement probe 1 having an excitation coil 4 and a detection coil 5 arranged so as to be wound around 2, and an induced voltage waveform detected by the magnetic characteristic measurement probe 1 is captured, processed, and induced And a harmonic measurement circuit 22 for measuring harmonics of the voltage waveform.

  The magnetic characteristic measurement probe 1 is the same as that in the first embodiment described above.

  The harmonic measurement circuit 22 is a form that further simplifies the first embodiment and emphasizes the features of the present invention that are small scale and small power.

  The harmonic measurement circuit 22 includes an AGC (Auto Gain Controlled Amplifier) unit 23 that receives the induced voltage waveform 12a detected by the detection coil 5 of the magnetic characteristic measurement probe 1 via the wiring 88, and A BPF (Band Pass Filter) unit 24 that extracts a frequency component corresponding to the third harmonic from the output of the AGC unit 23, and a result output unit 25 that holds and measures the peak value of the output of the BPF unit 24. And have.

  The AGC unit 23 is configured to adjust the gain so that the signal of the fundamental frequency becomes 1 with reference to the frequency of the power supply 11 that supplies the excitation current. The third harmonic component can be directly read by extracting the third harmonic component from the induced voltage waveform 12a adjusted to unity gain by the BPF unit 24 and holding the peak in the result output unit.

  The harmonic measurement circuit 22 according to the second embodiment can be configured with a simple analog circuit, and the excitation current can be reduced with a small electric power. Thus, a small and lightweight magnetic property measuring apparatus 20 can be realized. Since the harmonic measurement circuit 22 in the second embodiment has a small circuit scale and low power consumption, it can be used as a portable measuring instrument with a battery as a power source.

  If the magnetic characteristic measurement probe 1 and the power supply 11 used in the first embodiment and the second embodiment are prepared and a frequency analyzer such as a commercially available network analyzer is used, the detection coil 5 can be used. By measuring the frequency characteristic of the detected induced voltage waveform 12a, the presence or absence of heat treatment can be easily determined.

  DESCRIPTION OF SYMBOLS 1 Magnetic characteristic measurement probe, 2 Magnetic core, 3 Tip, 4 Excitation coil, 5 Detection coil, 6 Holding member, 7, 8 Wiring, 9 Magnetic substance to be measured 10, 20 Magnetic characteristic measuring apparatus, 11 Power supply, 11a Excitation current waveform, 12, 22 Harmonic measurement circuit, 12a Induced voltage waveform, 13 Waveform capture unit, 14 FFT unit, 15 Waveform analysis unit, 16 Result output unit, 23 AGC unit, 24 BPF unit, 25 Result output unit

Claims (12)

Magnetic characteristic measuring probe having a magnetic body having both ends, a first coil magnetically coupled to the magnetic body, and a second coil magnetically coupled to the magnetic body at a position different from the first coil When,
A power source for exciting the magnetic body by supplying a sinusoidal excitation current to the first coil;
A harmonic measurement circuit for acquiring an induced voltage waveform generated in the second coil by the excitation current and measuring a harmonic of the induced voltage waveform;
Measuring the magnetic properties of the measured magnetic material by contacting both ends of the magnetic material with the measured magnetic material, forming a closed magnetic circuit with the magnetic material, and measuring harmonics of the induced voltage waveform A magnetic property measuring apparatus characterized by:   2. The magnetic property measuring apparatus according to claim 1, wherein the magnetic body is formed by bending a laminated body of a ribbon-like amorphous alloy into a U shape along the longitudinal direction.   The first coil and the second coil are wound so as to be linked to a magnetic path of the magnetic body, and are disposed on both sides of the magnetic body, respectively. 3. The magnetic property measuring apparatus according to 1 or 2.   4. The magnetic property measuring apparatus according to claim 3, wherein both ends of the magnetic body form bent portions. The harmonic measurement circuit is
Waveform acquisition means for capturing the induced voltage waveform;
2. The magnetic characteristic measuring apparatus according to claim 1, further comprising: a harmonic component extracting unit that extracts a harmonic component of the induced voltage waveform captured by the waveform acquiring unit.   The waveform acquisition means includes an A / D conversion means for converting an analog signal into a digital signal, a storage means for temporarily storing data of the induced voltage waveform digitized by the A / D conversion means, and a storage means Frequency analysis means for reading out the data and performing frequency analysis; and output means for calculating a harmonic component from the frequency information data of the data generated by the frequency analysis means and outputting the calculation result, The magnetic property measuring apparatus according to claim 5.   The waveform acquisition means includes an automatic gain control amplifier that adjusts the level of the fundamental component to a predetermined value, and the harmonic component extraction means includes a band-pass filter whose center frequency is the frequency of the harmonic component. 6. The magnetic property measuring apparatus according to claim 5, wherein A magnetic body having both ends;
A first coil magnetically coupled to the magnetic body;
A second coil magnetically coupled to the magnetic body at a position different from the first coil,
The first coil is driven by a power source that generates a sinusoidal current,
The second coil outputs an induced voltage generated via the magnetic body excited by the first coil,
Measure the magnetic properties of the measured magnetic body by contacting both ends of the magnetic body with the measured magnetic body, forming a closed magnetic circuit with the magnetic body, and measuring harmonics of the induced voltage. A magnetic property measurement probe characterized by:   9. The magnetic characteristic measuring probe according to claim 8, wherein the magnetic body is formed by bending a laminated body of a band-shaped amorphous alloy into a U shape.   The first coil and the second coil are wound so as to be linked to a magnetic path of the magnetic body, and are disposed on both sides of the magnetic body, respectively. The magnetic property measurement probe according to 8 or 9.   The magnetic property measuring probe according to claim 10, wherein both ends of the magnetic body form bent portions. A magnetic body having both ends; a first coil magnetically coupled so as to excite the magnetic body; and a second coil magnetically coupled to the magnetic body at a position different from the first coil. Both ends of the magnetic body of the magnetic property measurement probe are brought into contact with the magnetic body to be measured so as to form a closed magnetic path with the magnetic body,
A power source supplies a sine wave current to the first coil to excite the magnetic body,
The induced voltage generated in the second coil by the excited magnetic material is acquired by the harmonic measuring circuit, and the harmonic characteristic is measured from the induced voltage, thereby measuring the magnetic characteristics of the measured magnetic material. Magnetic property measurement method.

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